Iron-N-heterocyclic carbene complexes (Fe-NHCs) have come to prominence because of their applicability in diverse catalytic reactions, ranging from C-C cross-coupling and C-X bond formation to substitution, reduction, polymerization, and dehydration reactions. The detailed synthesis, characterization, and application of novel heterogeneous Fe-NHC catalysts immobilized on mesoporous expanded high-amylose corn starch (HACS) and Starbon 350 (S350) for facile fructose conversion into 5-hydroxymethylfurfural (HMF) is reported. Both catalyst types showed good performance for the dehydration of fructose to HMF when the reaction was tested at 100 °C with varying time (10 min, 20 min, 0.5 h, 1 h, 3 h and 6 h). For Fe-NHC/S350, the highest HMF yield was 81.7 % (t=0.5 h), with a TOF of 169 h , fructose conversion of 95 %, and HMF selectivity of 85.7 %, whereas for Fe-NHC/expanded HACS, the highest yield was 86 % (t=0.5 h), with a TOF of 206 h , fructose conversion of 87 %, and HMF selectivity of 99 %. Iron loadings of 0.26 and 0.30 mmol g were achieved for Fe-NHC/expanded starch and Fe-NHC/S350, respectively.

The dehydration of fructose to 5-(hydroxymethyl)­furfural (HMF), catalyzed by Fe-NHC covalently tethered on spent mesoporous mango peel cellulose, is reported. The supported Fe-NHC catalyst shows excellent activity at 100 °C. HMF yield (71.0%), fructose conversion (97.5%), and HMF selectivity (71.5%) were achieved at t = 1 h, corresponding to a turnover frequency (TOF) of 79.2 h–1. Catalyst performance is comparable to traditional zeolites, such as Amberlyst-15, Montmorillonite K10, and ZSM-5, and can be reused.